Parachute air drop load impact reducing system

Abstract

A system for reducing the ground impact of a load in a parachute air drop system having the parachute canopy attached to a first platform and the load attached to a second platform. The first platform and second platform are connected together by a plurality of elastic cords. The elastic cords are held in a relaxed state by a steel cable connected between the platforms. A ground probe supported on a line a predetermined distance below the cargo load has switch contacts which close when the probe reaches the ground to operate a cable cutter. The cable cutter cuts the steel cable connected between the platforms to permit the cargo to free fall under the restraint of the elastic cords. The partially unloaded canopy and the air mass inertia under the canopy is used to slow the cargo load velocity just prior to touch down.

I claim: 
     
       1. In a parachute cargo load drop system having a parachute canopy with a cargo load supported beneath the parachute, a system for reducing load impact with the ground, comprising: a first platform; a plurality of shroud lines for securing said platform to the parachute canopy; a second platform spaced from said first platform; means for securing the cargo load to said second platform; an elastic support means, connected between said first platform and said second platform for elastically suspending the second platform from said first platform; means, connected between said first platform and said second platform for holding said elastic support means in a relaxed state; a ground sensing probe; means for supporting said ground sensing probe a predetermined distance below said cargo load; means, responsive to said ground sensing probe, for releasing said holding means when the cargo load is a predetermined distance from the ground to thereby permit the cargo load to free fall under the restraint of the elastic support means; said elastic support means including a plurality of elastic cords connected between the first platform and the second platform; said means for holding said elastic support means in a relaxed state including a steel cable connected between said first platform and said second platform; said means for releasing the holding means being a cable cutter adapted to cut said steel cable in response to a signal from said ground sensing probe. 
     
     
       2. The device as recited in claim 1 including a container secured to said load; said container being adapted to hold said ground sensing probe and the means for holding the probe a predetermined distance below the second platform; said container including a releasable door; a spring loaded latch for holding said door in its closed position. 
     
     
       3. The method for reducing the load impact with the ground in a parachute air drop system comprising: securing a parachute canopy to a first platform; securing a cargo load to a second platform; connecting the first platform to the second platform with a plurality of elastic cords; connecting a steel cable, shorter than the elastic cords between the first and second platforms to hold the elastic cords in a relaxed state; connecting a ground sensing probe to said load with a predetermined length of cord whereby the probe will contact the ground a predetermined time before the load; cutting the steel cable in response to said probe to permit the load to free fall under the restraint of said elastic cords thus permitting the parachute canopy to decelerate whereby the cargo drop velocity is restrained against the air mass inertia under the slowed canopy to permit cargo load touchdown at a velocity less than the parachute canopy velocity at the time of touchdown.